This document discusses different forms of energy including mechanical, heat, chemical, electromagnetic, and nuclear energy. It defines kinetic energy as the energy of motion and potential energy as stored energy. The document explains that energy can be converted from one form to another, but the total amount of energy remains constant due to the law of conservation of energy. Understanding energy and its transformations is important for studying physics and the physical sciences.

1. Energy: Forms and Changes
• The Nature of Energy
• Kinetic and Potential Energy
• Energy Conversions
• Conservation of Energy
• Physics and Energy

2. The Nature of Energy
• Energy can be defined as the ability to
do work.
• Energy is often measured in Joules (J).
• 1 Joule=1Kg-m2/sec2= 1 Nm
• Energy comes in many forms. The
main forms are: Mechanical, Heat,
Chemical, Electromagnetic, and
Nuclear.

3. The Nature of Energy
(continued)
• Mechanical energy is energy of motion.
• Examples include a moving car and
sound.
• Heat energy is energy of internal motion
(movement of atoms).
• Friction is one cause of heat energy.
• Chemical energy is stored in the bonds
that keep molecules together.

4. The Nature of Energy
(continued)
• Electromagnetic energy is caused by
moving charges.
• Examples include electricity and light.
• Nuclear energy is stored in the nucleus
of an atom.
• All stars (including our sun) run on
nuclear energy.

5. Kinetic and Potential Energy
• All of the types of energy just described
fit into one of two categories of energy:
Kinetic or Potential.
• Kinetic energy is the energy of motion.
• K.E.=(mass x velocity2)/2
• Kg x (m/sec)2=Kg-m2/sec2=Joule

6. Kinetic and Potential Energy
(continued)
• Potential energy is stored energy and is
sometimes called energy of position.
• For example, raising a bowling ball 1
meter above the ground gives it
potential energy relative to the ground.
• Gravitational Potential Energy (GPE)=
Weight x Height.
• Newtons x meters=Nm=Joule

7. Energy Conversions
• Energy can be converted from one form
to another.
• This process can happen over and over
again.
• For example, I can convert the
mechanical energy of rubbing my hands
together into heat energy.

8. Energy Conversions
(continued)
• One of the most common energy
conversions is Kinetic-Potential.
• For example, by holding a 20 Newton
bowling ball 1 meter above the ground,
it has 20 Joules of gravitational potential
energy.
• By releasing the bowling ball, its
potential energy is converted into
kinetic energy as it gains velocity.

9. Energy Conversions
(continued)
• As the bowling ball speeds up towards
the ground, its gravitational potential
energy is reduced, and its kinetic
energy is increased until the instant
before it hits the ground.
• At that point, the bowling ball has
converted all of its GPE into kinetic
energy, so that it now has 20 Joules of
kinetic energy.

10. Conservation of Energy
• The previous example shows how
energy is always conserved.
• In fact the Law of Conservation of
Energy says that energy can neither be
created nor destroyed by ordinary
means.
• Albert Einstein showed how energy can
be converted into mass and mass into
energy using his famous “E=mc2”

11. Conservation of Energy
(continued)
• The Law is consequently referred to as
“The Law of Conservation of
Mass-Energy.”

12. Physics and Energy
• Understanding energy is critical to
understanding the physical sciences.
• Everything we have studied in MFE
connects in some way to energy.
• For example, the faster you move, the
more momentum you have, the more
kinetic energy you have, the higher your
power, which means you consume
energy faster.